Visualizing Legal Rules: A Homicide Case

Legal rules can often be written as Mathematica expressions in which logical functions such as And or Or surround textual arguments relating to the various conditions needed to trigger some legal consequence. This fact, coupled with the flexible ways in which one can display a Mathematica expression, provides a new vehicle to readily visualize the structure of legal rules. This Demonstration illustrates this idea with a visualization of the law relating to the various forms of homicide. The user selects whether various factors that determine the form of homicide are present. The left panel of the output shows the possible charges that might be brought given the user's selections. The right panel shows a graph that explains the logical argument as to why any particular charge could or could not plausibly be brought. Green text and arrows mean that the factor is present or "true". Red text and arrows mean that the factor is absent or "false". If you hover your mouse over a control or a textual node in the graph in the right panel, a tooltip will appear that more fully explains the matter.


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Homicide laws vary from state to state as well as from nation to nation. This Demonstration provides a standard view of homicide law in the United States as set forth in American Jurisprudence, 2d, a leading legal encyclopedia.
If the state of mind is "premeditated" or the homicide occurs during a felony, the law seldom recognizes the existence of "provocation". This Demonstration thus disables the "provoked" control under these circumstances and sets the provocation variable to false.
Snapshot 1: first degree murder as a result of premeditation and a purposeful/knowing state of mind
Snapshot 2: second degree murder under the felony murder rule as a result of negligent conduct causing death during a felony
Snapshot 3: negligent homicide, which is unlikely to be prosecuted criminally
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